Liquid crystal displays (LCDs) are advantageous in being light, thin and having low power consumption. LCDs have been widely used in modern information devices such as notebook computers, mobile phones, and personal digital assistants (PDAs).
FIG. 1 shows an array substrate of a conventional liquid crystal display. The LCD array substrate 110 comprises a signal introducing region 111 and a display region 112. Data line pads 121 and scanning line pads 131 are formed in the signal introducing region 111. A plurality of data lines 122 and scanning lines 132 are respectively connected to the data line pads 121 and the scanning line pads 131. A plurality of pixels P is defined in an region where the data lines and the scanning lines cross. A data signal and a scanning signal are externally inputted via the data line pads 121 and the scanning line pads 131, and then transmitted to the respective pixels P in the display region 112 through the data lines 122 and the scanning lines 132.
In processes of manufacturing conventional LCD array substrates, defects such as break and the like may occur in the data lines. As shown in FIG. 1, the data line 122 is broken at a point D1 in the display region 112. In this case, a data signal cannot be transmitted to the data line below the break D1, thereby causing a so-called line defect.
In order to repair the line defect in the array substrate, U.S. Pat. No. 6,111,558 discloses a repair structure. In the structure, as shown in FIG. 2 of the present application, a data line 122 comprises three portions, that is, a front data line portion 122a outside the display region and connected with a data line pad 121, a display region data line portion 122b, and an end data line portion 122c outside the display region and at the side away from the data line pad 121. In addition, a repair line 223 is provided outside the display region 112 of the liquid crystal display. In the plan view of the array substrate of FIG. 2, the repair line 223 crosses with the front data line portion 122a and the end data line portion 122c perpendicularly. However, in a direction perpendicular to the surface of the array substrate, the repair line 223 and the data line 122 are positioned in different layers and separated by an insulating layer therebetween. Hence the repair line 223 and the data line 122 are normally not in an electrical connection.
When a break point D2 occurs as shown in FIG. 2, the front data line portion 122a and the repair line 223 are electrically connected at the crossing point A, and the end data line portion 122c and the repair line 223 are electrically connected at the crossing point B by laser melting. Thus, a data signal on the data line can be transmitted to the repair line 223 via the crossing point A through the front data line portion 122a, and then via the point B to the data line below the break point D2. In this manner, the line defect is repaired.
However, there are some disadvantages in the above repair structure. First, the material of the repair line 223 formed on a glass substrate is typically the same with that of the scanning line, for example Mo and AlNd, resulting a relatively large resistance. Second, when the front data line portion 122a and the end data line portion 122c are electrically connected by laser melting to the repair line 223 at the points A and B respectively, a parasitic capacitance may come out between the repair line 223 and other data lines because of being positioned in a crossing manner. Therefore, a delay will occur when a data signal is transmitted along the repair line 223. Furthermore, the parasitic capacitance will also affect signal transmission in other data lines.
In order to solve the above problem, US Patent Application Publication No. 2007/0040794A1 discloses another repair line structure. As shown in FIG. 3, the repair line structure is composed of a front repair line portion 325, an end repair line portion 323 and an intermediate repair line portion 324. The front repair line portion 325 is positioned outside a display region 112 and arranged perpendicular to a front data line portion 122a of a data line 122. However, the front repair line portion 325 and the data line 122 are positioned in different layers and separated by an insulating layer, and are normally not electrically connected. The end repair line portion 323 is positioned outside the display region 112 and arranged perpendicular to an end data line portion 122c of the data line 122. Also, the end repair line portion 323 and the data line portion 122 are positioned in different layers and separated by an insulating layer, and are normally not electrically connected. The intermediate repair line portion 324 is connected with the front repair line portion 325 and the end repair line portion 323 respectively. The intermediate repair line portion 324 can be formed on a printed circuit board (PCB) 340 and thus a material having high electric conductivity such as copper can be used. As a result, the resistance of the repair line is reduced.
When a break D3 occurs as shown in FIG. 3, the front data line portion 122a and the front repair line portion 325 are electrically connected at the crossing point A′, and the end data line portion 122c and the end repair line portion 323 are connected at the crossing point B′ by laser melting. Thus, a data signal on the front data line portion 122a can be transmitted to the intermediate repair line portion 324 on the PCB via the point A′, the front repair line portion 325 and the data line pad 121, and then to the data line below the break D3 via the end repair line portion 323 and the point B′. In this manner, the line defect is repaired.
In this repairing structure, the intermediate repair line portion 324 acts as a common repair signal line, which is connected with the front repair line portions of a plurality of repair lines. Therefore, when a data signal is transmitted in the intermediate repair line portion 324, the front repair line portions of the plurality of repair lines that are respectively connected to the intermediate repair line portion 324 will form parasitic capacitances with the data lines crossing with them, which can affect signal transmission.